Numerous approaches to particle processing as carried out by flow cytometers, cell sorters, and other cell separation systems have proven to be highly useful in such diverse life science applications as bioremediation, microbial fermentation, diagnostics, and other biomedical applications. Flow cytometers are systems that can measure large numbers of homogeneous or heterogeneous particle sets to achieve statistically relevant data sets that can be used to identify subpopulations within a given particle population. These measurements are often performed optically, or they may be electrical in nature when a stream of particles passes through an interrogation zone. With the addition of a sort functionality, a flow cytometer can further be used to isolate particle(s) of interest from a sample via operator control. This technique can be used to process particle populations as defined by the operator. One common cell separation method uses electrostatic forces to divert an electrically or electrostatically charged stream, droplet, or droplets containing a cell or cells having specific properties. The diverted cells are subsequently processed as appropriate to the particular application.
Conventional systems for processing particles typically rely on a number of nonintegrated fluidic components, which are unwieldy and may result in contamination problems. U.S. Pat. No. 6,079,836 discloses an example of a prior art particle processing system wherein several different components form the fluidic contact surfaces and surfaces contiguous to the droplet formation, sorting, and collection regions are not sealed from the external surrounding environment. For example, in conventional particle sorting systems, the particles to be sorted form a suspension in a liquid medium that passes through or is contained within a collection of fluid contact surfaces. In conventional droplet sorters, the suspension passes through a nozzle and is formed into a stream of droplets (the aerosol phase) before being captured in collection vessels. The droplet stream and associated aerosol can touch or contaminate any area within the system that is not sealed away from the stream. Crucially, in many particle processing applications, either or both of “operator isolation” and “product isolation” must be ensured. “Operator isolation” refers to protecting the operator from exposure to the particle suspension, for example, when there is a possibility of infectious disease agents or other noxious material existing within the suspension. “Product isolation” refers to isolation of the suspension from contamination with traces from outside the suspension, including contamination from the environment or from prior suspensions that have passed through the sorting system. Product isolation also refers to isolating the instrument from the product. Conventional sorting systems and other particle processing systems thus require operation in chambers (such as biohoods) to provide operator isolation. However, these types of systems are difficult to service as they require replacement and/or cleaning of all of the fluid contact surfaces in order to guarantee product isolation and the manual steps required represent a risk to personnel. Further, in a climate where ease of use is increasingly prioritized, such systems fall short.